Novartis said it has initiated a study to compare its breast cancer drug Femara (letrozole) with AstraZeneca’s best-selling Arimidex (anastrozole), The Wall Street Journal reported.
Novartis said the study will look at 4,000 patients around the world. It is the first trial that will compare the two medicines in use after breast cancer surgery.
Last year Femara totaled $536 million in sales, compared with around $1.18 billion for Arimidex.
AstraZeneca called the study a marketing move.
A spokesperson for AstraZeneca told the Journal that the trial would be open-label, meaning that both doctors and patients will know which drugs are being used, unlike clinical studies required to obtain regulatory approval. “There is no scientific rationale for doing this,” the spokesperson said.